Method of and apparatus for making blanks



y 0, 1933. w. D. CORLETT METHOD OF AND APPARATUS FOR MAKING BLANKS FiledOct. 10, 1931 Patented May 30, 1933 UNll El isuaso D. COBLETT, OFCHICAGO, Ill-ILLINOIS, ASSIGIIOR TO STANDARD SCREW GOM- PANY, OFHARTFGR-D, GGNNECEIG'UT, A CORIPORA'EIGN OF NEW JERSEY METHOD OF ANDAPFARATUS FOE lt'IAKIIIG BLANIKS Application filed Gctober 10, 1931.

This invention relates to a method of and apparatus for forming blanks.As illustrated herewith, it has particular reference to the formation ofblanks which may subsequently be made into screws, bolts, rivets, studs,or other generally similar parts, although it is not limited to thatparticular use.

It has for one object to provide a method of forming blanks havingshanks which will be accurate in size and shape. Another object is toprovide means whereby accurate blanks can be formed by dies frommaterial which is relatively inaccurate in size, shape and finish at thetime that it is used and from material of a class which has heretoforebeen considered unsuitable for use in the formation of accurate blanks.Another object is to provide means for increasing the die life bygreatly reducing the wear on the forming dies. Another object is toprovide a method of finishing a blank accurately to size by means of adie after it has been initially formed.

Other objects will appear from time to time in the specification andclaims.

The method is illustrated in the following drawing, which showsdiagrammatically the dies and the blank in several stages.

Figure l is a cross section illustrating the initial forming die. Asshown this is a double ended die. A single ended die might be used;

Figure 2 is a cross section of the secondary forming or extruding die,showing a partially formed blank in position therein;

Figure 3 is a side elevation of one form of blank at an intermediatestage in its formation;

Figure 4 is a side elevation of the same form of blank upon completion;

Figure 5 is a side elevation of a different form of blank at anintermediate state corresponding to that shown in Figure 3. This form ofblank is preferably made from the blank in the condition shown in Figure3;

Figure 6 is a side elevation showing the blank of Figure 5 completed;and

Figure 7 illustrates a modified arrangement of the dies.

Serial No. 568,009.

Like parts are designated by like characters throughout thespecification and draw- 111g.

The process in one manner may be applied to the forming of cap screws,bolts, rivets and upset products. Heretofore such products have beenmade on cold heading machines. They are usually made from continuousstrips of wire which is cut ofi in any suitable manner in appropriatelengths. Such lengths are driven or otherwise inserted into a die whichheretofore has been cylindrical. A portion of the end is allowed toprotrude and sufficient pressure is exerted upon this, by striking 0rotherwise, in a single or multiple operation. to cause it to be enlargedlaterally and thus producing a head. By this method, blanks such asthose shown in Figure 4 may be formed. The process is relativelyexpensive, however, and the wear on the dies is great and their life iscorrespondingly short. I prefer, in my method, to use a die which istapered. In ordinary practice this is a relatively slight taper. Forpurposes of illustration, it is necessary to greatly exaggerate theshowing of this taper in the drawing.

In Figure 1 I show a die A, which is provided with a tapered bore Awhich may have a counter-sunk head forming portion A As shown the die isalso provided with a tapered portion A and a counter-sunk head formingportion A". The die is thus in effect a double die. If desired, one endmay be used and after it is worn the other end may be used. I could, ofcourse, use a single die, solid or open dies. v

An appropriate length of wire is inserted in the tapered bore A Pressureis then exerted upon its end so that it is enlarged to form a head. Theblank is then pushed or struck from the inner end through theperforation in the die and ejected. Because of the taper of the here A avery slight movement of the blank completely frees it from the die andit may thus be moved with a minimum of friction upon the parts. 7

As illustrated in Figure 3, the blank is shown after the completion ofthe operation above just described. It has a tapered shank portion B anda laterally extending head member B It is now ready for the secondoperation which will give it a true and accurate cylindrical shape,removing the taper. To accomplish this second step, I use an extrudingdie G. This die is provided with a straight portion C and is cut away,enlarged or relieved as at C It is preferably beveled as at C Thediameter of the straight portion of the die C is greater than that ofthe end of the tapered shank member B. The latter may thus be easilyinserted into the extruded die for a portion of its length. To completethe insertion of the blank, pressure is exerted. The blank is thusforced fully into the die to the position shown in Figure 2, and aportion indicated as at X is made straight or reduced to a true oraccurate cylindrical shape. At this stage of the operation, the portionindicated at Y remains tapered and is of smaller diameter than theopening through the extruding die. The inner or tapered end of the blankis then contacted by a member D which may be of any suitable size orshape and operated in any desired manner or by any suitable mechanism,and the blank is moved in a reverse direction andout of the die. When itis so moved a re-extruding operation takes place and the straightportion C of the extruding die causes the metal to flow along and towardthe tapered end and when the blank has been completely forced from thedie it is found to have been made truly and accurately cylindricalthroughout its length. I thus, by the several steps of my process,produce an accurate blank which is cylindrical and true to shape anddimension within extremely narrow tolerances and which is at once readyfor threading or other operations in case any such are desired.

In the methods heretofore used in forming blanks, it has been necessaryto have wire or stock which is itself made accurately and to closetolerances. It has, therefore, been considered necessary to use what isgenerally referred to as cold drawn wire. This wire is relativelyexpensive. In my method, particularly because of the extrud-. ing step,I reduce the blank to the proper shape within very close tolerances andI am able to use What is commonly called hot rolled wire which asfurnished is less accurate in shape and size than cold drawn wire andwhich is appreciably cheaper.

For many purposes it is desirable to make blanks having shouldersintermediate their ends. Such a blank is shown in Figure 5, in anintermediate stage of its manufacture, and in Figure 6 it is showncompleted.

Then it is desired to make a blank having a shoulder, the initial stepsof the process are usually the same as those described above. A piece ofwire of suitable length is inserted in the bore A of the die and by thesteps above described is formed into a blank such as that shown inFigure 3. It is then forced through an extruding die such as that shownin Figure Q-but it is not forced entirely through the die. A die ofsuitable size is chosen and the blank is forced through the die only tothe point E at which it is desired to form the shoulder. The primaryextruding operation is thus carried out only for a portion E of thelength of the blank. The blank is then forced from the extruding die andthe re-extruding operation takes place and thus the portion of the blankup to the point where the shoulder is to be formed, is reduced to anaccurate cylindrical. shape. A portion of the blank E still remainstapered as shown in Figure 5. Subsequently that tapered portion isforced into a second and somewhat larger extruding die and it isextruded and re-extruded to reduce that portion to cylindrical shape, asindicated in Figure 6, and thus the completed blank is formed with twocylindrical portions E and E one of larger size than the other, and thetwo separated by the shoulder E.

When any of the extruding processes is carried out, the excess metal allgoes into the elongation. None is scraped off or in any way removed. Itwill be noticed from the drawing that the finished blank of Figure 4- islonger than the blank of Figure 3 and that the finished blank of Figure6 is longer than the unfinished blank of Figure 5. The fillet-likeportion shown adjacent the head of the blank in the forms illustrated inFigures 2, 4t and 6, may be allowed to remain, or if desirable, may beremoved in any suitable manner.

No matter what; form of die I use, and no matter how the details of mymethod are modified, so long as I adhere generally to my method I amable to make extremely accurate blanks. In the past, even by separatemachining of the separate parts, which is a relatively slow andexpensive process, it has been impossible to hold the dimensions of suchproducts with which I am dealing to tolerances closer than two or threethousandths of an inch. By my method, which is cheaper and more rapid,and which is accomplished with a tremendously increased die life, I amable to hold my product to tolerances of less than one-ten-thousandth ofan inch.

Figure 7 illustrates a modified die arrangement by means of which ashouldered blank such as that shown in Figures 5 and 6 may be made. Asthus shown, a die F, pro vided with a tapered bore F and a head formingdepression F may be used. To this i tapered.

tion has at one end an inclined face G The perforation G is restrictedas at G to pro- '*ide a cylindrical extruding portion of the die. H is ahousing member provided with a perforation H corresponding generally inshape to the perforation G of tlie extruding die ant. in alignment withit. H is a mem ber mounted to be positioned within the perforation H andto move therein. It serves as a stop to limit the inward movement of theblank during the initial forming movement and serves also when it isdriven further inward, as the forming movement is completed, to ejectthe blank.

In the use of the die arrangement shown in Figure '7, the stop member His moved to the proper position and held there. A piece of wire of theproper length is then forced into the tapered portion and through it andpartially through the extruding die,

iintil it strikes the stop H thus causing some extrusion of that portionof the memher which has passed through the extruding portion G of theextruding die G Once '1 the wire has come in contact with the stop H itsfurther inward movement is stopped .nd further pressure on its outer orexposed end causes it to swell into the tapered portion of th die. Afterthis operation is completed, the member which has forced the blank intothe die is withdrawn or removed and the stop H is then forced fartherinward or to the right, as shown in Figure 7, to eject the blank. Inthis movement the extruding of the inner portion of the blank iscompleted so that when it leaves the die it is generally in thecondition shown in Figure 5, with its smaller end properly reduced tocylindrical shape and its thicker portion Subsequently the thickertapered portion remaining is reduced to cylindrical shape in the mannerdescribed above.

It will be realized that whereas I have herewith shown and described apractical operative device, nevertheless many changes might be made inthe size, shape, number and disposition of parts without departing fromthe spirit of my invention and I wish, therefore, that my showing betaken as in a sense diagrammatic.

The clearances, particularly within the extruding dies and associatedparts, are of necessity exaggerated in the drawing. Otherwise thedetails would not be intelligible. The clearance of the member I-Iwithin the bore or performation H and the clearance within theperforation G is exaggerated. Actually the clearance is relativelyslight and the parts may be in contact with each other, but the diameterof the bore H and the perforation G is larger than that of therestricted or working portion G of the extruding die G. The same appliesto the extruding die as shown in Figure 2.

I claim:

1. The method of forming a metallic blank, which includes the followingsteps: Acting upon a piece of metal of suitable size and shape andforming it into a tapered shank and thereafter changing said taperedshank into a cylindrical shank by first extruding a portion of saidshank to reduce it to cylindrical shape and subsequently extruding theremainder of the shank and re ducing it to a cylindrical shape.

2. The method of forming a metallic blank, which includes the followingsteps: Acting upon a piece of metal of suitable size and shape andforming it into a tapered shank and thereafter changing said taperedshank into a cylindrical shank by first extruding a portion of saidshank to reduce it to cylindrical shape and subsequently extruding in areverse direction the remainder of the shank and reducing it to acylindrical shape.

3. The method of forming a metallic blank which includes the followingsteps: Acting upon a piece of metal of suitable size and shape andforming it into a tapered shank and thereafter changing said taperedshank into a cylindrical shank by first extruding a portion of saidshank to reduce it to cylindrical shape and subsequently extruding theremainder of the shank and re ducing it to a cylindrical shape of thesame diameter as that of the first portion.

4. The method of forming a metallic blank, which includes the followingsteps: Acting upon a piece of metal of suitable size and shape andforming it into a tapered shank and thereafter changing said taperedshank into a cylindrical shank by first extruding a portion of saidshank to reduce it to cylindrical shape and subsequently extruding in areverse direction the remainder of the shank and reducing it to acylindrical shape of the same diameter as that of the first portion.

5. The method of forming a metallic blank, which includes the followingsteps: Acting upon a piece of material, imparting to it a tapered shapeand removing the taper by forcing the tapered portion through a die,first in one direction to remove a portion of the taper, and second inthe reverse direction, to remove the remainder of the taper.

6. The method of forming a metallic blank, which includes the followingsteps: Acting upon a piece of generally rod-like material, imparting toit a tapered shape and removing the taper by forcing the tapered portionthrough a die, first in one direction to remove a portion of the taper,and second in the reverse direction to remove the remainder of thetaper.

7 The method of forming a metallic blank which includes the followingsteps: Acting upon a piece of material, imparting to it a taered shape,and removing the taper by forcing the tapered portion through a die ofgreater diameter than the smallest diameter of the taper, first in onedirection to remove a portion of the taper, and second in the reversedirection to remove the remainder of the taper.

8. The method of forming a metallic blank, which includes the followingsteps: iact' ig upon a piece of generally rod-like material, impartingto a tapered shape, and removing the taper in two steps, by forcing thetapered portion through a die of greater diamete than the smallestdiameter of the taier, first in one direction, to remove a portion ofthe taper, and second in the reverse direction to remove the remainderot' the taper.

9. The method of forming a metallic blank, which includes the followingsteps: Acting upon a piece of generally rod-like material, forming ahead upon it and imparting to the rod-like portion tapered shape, andremoving the taper in two steps, by forcing the tapered portion throughdie, of greater diameter than the smallest diameter of the taper, firstin one direction to remove a portion of the taper, and second in thereverse direction remove the remainder of the taper.

10. The method tr forming a metallic blank which includes he followingsteps: Extruding a portion 0 a piece of metal of a suitable size andshape to form it into cylindrical shape, forming another portion or"said piece of metal into a tapered shanl' extruding the tapereo portionto reduce itto cylindrical shape.

11. The method of forming a metallic blank which includes the followingsteps: Ext-ruding a portion of a piece of metal of a suitable size andshape to form it into cylindrical shape, forming another portion of saidpiece of metal into a tapered shank, and subsequently extruding thetapered portion to reduce it to cylindrical shape.

12. The method of forming a metallic blank which includes the followingsteps:

Extruding a. portion of a piece of metal of a suitable size and shape toform it into cylindrical shape, forming another portion of said piece ofmetal into a tapered shank, and subsequently and separately extrudingthe tapered portion to reduce it to cylindrical shape.

13. The method of forming a metallic blank which includes the followingsteps: Extrudin a port-ion of a piece of metal of a suitable size andshape to form it into cylindrical shape, forming another portion of saidpiece of metal into a tapered shank, re-extruding the extruded portionand ex truding the tapered portion to reduce it to cylindrical shape.

14. The method of forming a metallic blank which includes the followingsteps Extruding a portion of a piece of metal of a suitable size andshape to form it into cylindrical shape, forming another portion of saidpiece of metal into a tapered shank, re-extruding the extruded portionand subsequently and separately extruding the tapered portion to reduceit to cylindrical shape.

15. The method of forming a metallic blank which includes the followingsteps: Extruding a portion of a piece of metal of a suitable size andshape to form it into cylindrical shape, and simultaneously forminganother portion of said piece of metal into a tapered shank, extrudingthe tapered portion to reduce it to cylindrical shape.

16. The method of forming a metallic blank which includes the followingsteps: Extruding a portion of a piece of metal of a suitable size andshape to form it into cylindrical shape, and simultaneously torminganother portion oi"- said piece of metal into a tapered shank, andsubsequently and separately extruding the tapered portion to reduce itto cylindrical shape.

17. The method of forming a metallic blank which includes the followingsteps: Ext-ruding a port-ion of a piece of metal of a suitable size andshape to form it into cylindrical shape, and simultaneously forminganother portion 01 said piece of metal into a tapered shank,re-extruding the extruded portion and subsequently and separatelyextruding the tapered portion to reduce it to cylindrical shape.

Signed at Chicago, county of Cook and State of Illinois, this 9th day ofSeptember 1931.

WEBSTER D. CORLETT.

